BOSTON (CBS) — It’s happening again.

After a prolonged dispute between Major League Baseball and the players’ union last year led to the season being shortened to just 60 games, the two sides are once again at odds regarding the length and start date to the 2021 season.

That’s according to USA Today’s Bob Nightengale, who reported Tuesday that MLB executives and team owners want players to be vaccinated for COVID-19 before the season begins.

“The issue that could further erode the trust between the two groups is whether owners take the stance that the season should be delayed until every player and staff member gets the vaccine,” Nightengale wrote.

One anonymous National League team owner told Nightengale that there’s not “a snowball’s chance in hell” for the season to start on time, without the players getting vaccinated. An American League owner said there’s “zero chance” of spring training starting in February.

“If [spring training] has to be moved back to April and play 130 games, so be it,” the NL owner told Nightengale.

MLB went through its season last year with some ups and downs, with some teams’ schedules being disrupted significantly and with other teams going through the season without much, if any, interruption. The Los Angeles Dodgers eventually beat the Tampa Bay Rays in the World Series, which took place in a centralized location.

Notably, the collective bargaining agreement is set to expire after the 2021 season. Last year’s dispute didn’t exactly smooth many edges between the two sides, and if another dispute arises from the start date of the 2021 season, the prospect of labor peace in baseball looks dicey.